The present invention relates to a coating apparatus, and more particularly to a coating apparatus for coating a primer to a window glass panel to be mounted in an automobile body, the coating apparatus having a head member slidable along an area of the window glass panel which is to be coated with an adhesive, the head member having a coating material outlet for supplying a primer and slidable to spread the supplied primer over the area.
When installing a window glass panel in an automobile body, for example, an adhesive is coated on the peripheral edge of the window glass panel, and the window glass panel is firmly attached to the automobile body by the bonding strength of the adhesive. For keeping the adhesive firmly bonded to the window glass panel, it is general practice to coat the peripheral edge of the window glass panel, i.e., an area of the window glass pane where the adhesive will be applied, with a primer before the adhesive is coated.
Heretofore, a brush has been used in many instances to coat a primer on a window glass panel. According to one known coating process, for example, a brush is installed on a robot arm and slidably displaced along an area of the window glass panel to be coated, while at the same time a metered amount of primer is supplied to the brush, for thereby automatically coating the primer on the entire area.
The above conventional coating process is however disadvantageous in that since the primer is applied using the brush, it is difficult to apply a primer coating layer of a desired width and a uniform thickness to the area. The coated primer may be applied to a portion of the window glass panel where no primer coating should be applied, and the coated primer layer may not have a sufficient thickness which is thick enough to remain well adhered to an adhesive which will be applied subsequently.
Moreover, after the primer has been coated, the solvent contained in the primer retained in the brush may be evaporated making the surface of the bush hard before the brush will be used in a next coating process. If the brush with the hard surface were used again in the next coating process, it would be impossible to provide a primer coating layer having a uniform layer thickness. As a result, a tedious maintenance procedure is required to keep the brush ready for use at all times.
Another problem with the use of the brush is that the brush is not highly durable and cannot remain usable continuously for a long period of time.